Field of the Invention
This invention lies in the field of washing coal with water only in a shallow bottomed centrifugal separating cyclone of circular cross-section having a cylindrical portion with a diameter to height ratio of 0.8 to 1.3, preferably 0.90 to 0.95, the cyclone fitted with a single inlet pipe, a shallow dish below the cylindrical portion, a single bottom orifice fitted to the shallow dish and a fixed vortex finder leading to an outlet at the top for removal of washed coal. Gravity separation under streamlined flow is accomplished with light coal particles at a gravity value down to about 1.3 using crushed coal ranging in size from 13/4".times.0 down to 3/8".times.0.
The invention also lies in the field of providing an easily insertable abrasion resistant bottom dish having unique toughness and wear resistance characteristics to provide trouble-free, efficient coal washing based on the special material characteristics and the critical geometry of the shallow bottom dish which adapts it to fit in a closely contoured relationship to the cylindrical portion of the cyclone.
Further, the invention lies in the field of rebuilding cyclones to include the insertable dish and orifice and set the critical adjustments of the invention.
The invention also lies in the field of cleaning ores other than coal to rid them of impurities by taking advantage of the newly discovered efficiency and capacity taught in the present application.